A conventional muffler connected to an exhaust pipe of an internal combustion engine as shown in FIG. 6 includes: an expansion chamber EC, a resonating chamber R and several perforated pipes P enclosed with glass fibers or other sound-wave absorbing materials R for noise silencing purpose. However, an engine exhaust gas, before leaving from such a muffler, will flow through the perforated pipes to delay its discharge movement and to cause back pressure against an engine cylinder, thereby resulting in an incomplete combustion of gas mixture inside the engine and counteracting the engine output.
The present inventor has found these phenomena and invented the present tail pipe for drafting an engine exhaust gas.